#include <Functions/IFunction.h>
#include <Functions/castTypeToEither.h>
#include <Functions/FunctionFactory.h>
#include <DataTypes/DataTypesNumber.h>
#include <DataTypes/DataTypeNullable.h>
#include <Core/ColumnNumbers.h>
#include <Columns/ColumnNullable.h>


namespace DB
{
namespace ErrorCodes
{
    extern const int BAD_ARGUMENTS;
    extern const int ILLEGAL_COLUMN;
}

namespace
{

/// Returns 1 if argument is zero or NULL.
/// It can be used to negate filter in WHERE condition.
/// "WHERE isZeroOrNull(expr)" will return exactly the same rows that "WHERE expr" will filter out.
class FunctionIsZeroOrNull : public IFunction
{
public:
    static constexpr auto name = "isZeroOrNull";

    static FunctionPtr create(ContextPtr)
    {
        return std::make_shared<FunctionIsZeroOrNull>();
    }

    std::string getName() const override
    {
        return name;
    }

    size_t getNumberOfArguments() const override { return 1; }
    bool useDefaultImplementationForNulls() const override { return false; }
    bool useDefaultImplementationForConstants() const override { return true; }
    bool isSuitableForShortCircuitArgumentsExecution(const DataTypesWithConstInfo & /*arguments*/) const override { return false; }
    ColumnNumbers getArgumentsThatDontImplyNullableReturnType(size_t /*number_of_arguments*/) const override { return {0}; }

    DataTypePtr getReturnTypeImpl(const DataTypes & types) const override
    {
        if (!isNumber(removeNullable(types.at(0))) && !isNothing(removeNullable(types.at(0))))
            throw Exception(
                ErrorCodes::BAD_ARGUMENTS, "The argument of function {} must have simple numeric type, possibly Nullable or Null", name);

        return std::make_shared<DataTypeUInt8>();
    }

    ColumnPtr executeImpl(const ColumnsWithTypeAndName & arguments, const DataTypePtr &, size_t input_rows_count) const override
    {
        if (isNothing(removeNullable(arguments[0].type)))
            return DataTypeUInt8{}.createColumnConst(input_rows_count, 1);

        const ColumnPtr & input_column = arguments[0].column;

        ColumnPtr res;
        if (const ColumnNullable * input_column_nullable = checkAndGetColumn<ColumnNullable>(input_column.get()))
        {
            const NullMap & null_map = input_column_nullable->getNullMapData();
            const IColumn * nested_column = &input_column_nullable->getNestedColumn();

            if (!castTypeToEither<
                ColumnUInt8, ColumnUInt16, ColumnUInt32, ColumnUInt64,
                ColumnInt8, ColumnInt16, ColumnInt32, ColumnInt64,
                ColumnFloat32, ColumnFloat64>(
                nested_column, [&](const auto & column)
                {
                    auto col = ColumnUInt8::create(input_rows_count);
                    processNullable(column.getData(), null_map, col->getData(), input_rows_count);
                    res = std::move(col);
                    return true;
                }))
            {
                throw Exception(
                    ErrorCodes::ILLEGAL_COLUMN,
                    "The argument of function {} must have simple numeric type, possibly Nullable or Null",
                    name);
            }
        }
        else
        {
            if (!castTypeToEither<
                ColumnUInt8, ColumnUInt16, ColumnUInt32, ColumnUInt64,
                ColumnInt8, ColumnInt16, ColumnInt32, ColumnInt64,
                ColumnFloat32, ColumnFloat64>(
                input_column.get(), [&](const auto & column)
                {
                    auto col = ColumnUInt8::create(input_rows_count);
                    processNotNullable(column.getData(), col->getData(), input_rows_count);
                    res = std::move(col);
                    return true;
                }))
            {
                throw Exception(
                    ErrorCodes::ILLEGAL_COLUMN,
                    "The argument of function {} must have simple numeric type, possibly Nullable or Null",
                    name);
            }
        }

        return res;
    }

private:
    template <typename InputData>
    void processNotNullable(const InputData & input_data, ColumnUInt8::Container & result_data, size_t input_rows_count) const
    {
        for (size_t i = 0; i < input_rows_count; ++i)
            result_data[i] = input_data[i] == 0;
    }

    template <typename InputData>
    void processNullable(const InputData & input_data, const NullMap & input_null_map,
        ColumnUInt8::Container & result_data, size_t input_rows_count) const
    {
        for (size_t i = 0; i < input_rows_count; ++i)
            result_data[i] = input_null_map[i] || input_data[i] == 0;
    }
};

}

REGISTER_FUNCTION(IsZeroOrNull)
{
    FunctionDocumentation::Description description = R"(
Checks if the argument is either zero (`0`) or `NULL`.
    )";
    FunctionDocumentation::Syntax syntax = "isZeroOrNull(x)";
    FunctionDocumentation::Arguments arguments = {
        {"x", "A numeric value.", {"UInt"}}
    };
    FunctionDocumentation::ReturnedValue returned_value = {"Returns `1` if `x` is `NULL` or equal to zero, otherwise `0`.", {"UInt8/16/32/64", "Float32/Float64"}};
    FunctionDocumentation::Examples examples = {
    {
        "Usage example",
        R"(
CREATE TABLE t_null
(
  x Int32,
  y Nullable(Int32)
)
ENGINE = MergeTree
ORDER BY tuple();

INSERT INTO t_null VALUES (1, NULL), (2, 0), (3, 3);

SELECT x FROM t_null WHERE isZeroOrNull(y);
        )",
        R"(
┌─x─┐
│ 1 │
│ 2 │
└───┘
        )"
    }
    };
    FunctionDocumentation::IntroducedIn introduced_in = {20, 3};
    FunctionDocumentation::Category category = FunctionDocumentation::Category::Null;
    FunctionDocumentation documentation = {description, syntax, arguments, returned_value, examples, introduced_in, category};

    factory.registerFunction<FunctionIsZeroOrNull>(documentation);
}

}
